Truncus Arteriosus
Information for teenagers and adults with repaired truncus arteriosus
Truncus arteriosus is a rare congenital heart condition in which a baby is born with one large blood vessel leaving the heart instead of two separate arteries.
Normally, the right ventricle pumps blood through the pulmonary artery to the lungs, while the left ventricle pumps blood through the aorta to the rest of the body.
In truncus arteriosus, a single large artery — called the truncal artery — leaves the heart and supplies both the lungs and the body.
There is also usually a large ventricular septal defect (VSD) between the two pumping chambers of the heart.
Truncus arteriosus requires surgery early in life. Most teenagers and adults with truncus arteriosus have therefore had one or more heart operations during childhood.
Modern treatment allows many people with repaired truncus arteriosus to reach adulthood and lead active lives. However, further procedures are often required over a lifetime, so lifelong care with an adult congenital heart disease specialist is important.
How is the heart different in truncus arteriosus?
During normal development, the single blood vessel leaving the early fetal heart divides into two separate arteries:
The aorta, which carries oxygen-rich blood to the body
The pulmonary artery, which carries blood to the lungs
In truncus arteriosus, this separation does not occur completely.
Instead, there is one large vessel leaving the heart.
The valve controlling blood flow into this vessel is called the truncal valve.
The truncal valve may have a different number or arrangement of leaflets compared with a normal aortic valve. It may function normally, but in some people it can be narrowed or leak.
Because there is usually a large VSD, blood from both ventricles can enter the truncal artery.
Without treatment, this results in excessive blood flow through the lungs and places considerable strain on the heart.
How is truncus arteriosus repaired?
Truncus arteriosus is usually repaired during early infancy.
The operation separates the circulation so that the left ventricle pumps blood to the body and the right ventricle pumps blood to the lungs.
This usually involves:
Closing the VSD so that the left ventricle pumps directly into the truncal artery
Using the original truncal artery as the new aorta
Separating the pulmonary arteries from the truncal artery
Creating a new connection from the right ventricle to the pulmonary arteries
This new connection is usually made using a tube containing a valve, known as an RV–PA conduit.
After repair, the circulation is much closer to normal, but the heart still has important differences that require lifelong monitoring.
What is an RV–PA conduit?
An RV–PA conduit is a tube connecting the right ventricle to the pulmonary arteries.
It allows the right ventricle to pump blood to the lungs after the original pulmonary arteries have been separated from the truncal artery.
These conduits do not last forever.
A conduit placed in a baby or young child does not grow as the child grows. Over time it can also become narrowed, calcified or leaky.
For this reason, most people with truncus arteriosus will require replacement of their RV–PA conduit at some stage, and many require more than one conduit replacement during their lifetime.
The timing varies considerably between individuals.
What can happen to the pulmonary valve or conduit?
Two main problems can develop.
Conduit or pulmonary stenosis
The conduit may gradually become narrowed, making it more difficult for the right ventricle to pump blood to the lungs.
This increases pressure within the right ventricle.
Pulmonary regurgitation
The valve within the conduit may become leaky, allowing blood to flow backwards into the right ventricle after each heartbeat.
Significant pulmonary regurgitation can gradually cause the right ventricle to enlarge.
Your congenital cardiologist will monitor both the conduit and the right ventricle to determine whether another intervention is required.
Will I always need open-heart surgery to replace the conduit?
Not necessarily.
Traditionally, a failing RV–PA conduit was replaced with another operation.
For some people, it is now possible to place a new pulmonary valve using a catheter procedure. This is called transcatheter pulmonary valve replacement.
A new valve is delivered through a blood vessel and positioned inside the existing conduit or previous valve.
Whether this is possible depends on the size and shape of the conduit, the relationship of the coronary arteries and other individual anatomical factors.
Some people will still require surgical conduit replacement.
Your congenital heart team can determine which approach is most appropriate when intervention becomes necessary.
What happens to the truncal valve?
After repair, the original truncal valve becomes the valve between the left ventricle and the aorta. It therefore functions as the body’s aortic valve.
The valve may leak. This is called truncal valve regurgitation, or aortic regurgitation after repair.
Less commonly, the valve can become narrowed.
Mild truncal valve regurgitation may remain stable for many years.
More significant regurgitation can cause the left ventricle to enlarge and may eventually require surgery to repair or replace the valve.
What about the aorta?
The original truncal artery becomes the aorta after repair.
The aortic root can be larger than usual in people with truncus arteriosus and may become progressively enlarged over time.
Your cardiologist will therefore monitor the size of the aorta as well as the function of the truncal valve.
An enlarged aorta does not necessarily require treatment. Surgery may be considered if it becomes very large, grows significantly over time or needs to be addressed during another heart operation.
Are the pulmonary arteries important?
Yes.
The pulmonary arteries can sometimes become narrowed, particularly near previous surgical connections.
Narrowing may involve the main pulmonary artery or one of the branches supplying the right or left lung.
Depending on the anatomy, pulmonary artery narrowing may sometimes be treated with a balloon or stent during a cardiac catheter procedure. Other people require surgical treatment.
Heart rhythm problems
People with repaired truncus arteriosus can develop abnormal heart rhythms, particularly after multiple heart operations.
These may arise from either the upper or lower chambers of the heart.
Tell your congenital heart team if you develop new palpitations, unexplained dizziness, fainting or a noticeable deterioration in exercise capacity.
Some people require medication, an electrophysiology procedure or, less commonly, a pacemaker or defibrillator.
Will I need more heart procedures?
Many people with truncus arteriosus require additional procedures during their lifetime.
This does not necessarily mean that the original repair has failed.
The need for further procedures is often an expected consequence of having a conduit or valve that has been present since childhood.
Future procedures may include:
RV–PA conduit replacement
Transcatheter pulmonary valve replacement
Pulmonary artery ballooning or stenting
Truncal/aortic valve repair or replacement
Surgery on an enlarged aortic root
Treatment of abnormal heart rhythms
Advances in catheter-based treatment mean that some procedures that previously required open-heart surgery can now be performed without another major operation.
How to stay well
Keep up with your congenital heart checks
People with repaired truncus arteriosus require lifelong follow-up with an adult congenital heart disease specialist.
Even if you feel completely well, regular assessment is important because conduit, valve and ventricular problems can develop gradually before causing obvious symptoms.
Your congenital heart team will monitor:
The RV–PA conduit or pulmonary valve
Right ventricular size and function
Truncal/aortic valve function
Left ventricular function
Aortic root size
Pulmonary arteries
Heart rhythm
Exercise capacity
Stay active
Regular physical activity is encouraged for most people with repaired truncus arteriosus.
The type and intensity of exercise that is appropriate depends on your conduit, heart valves, ventricular function, aortic size and heart rhythm.
People with a good repair and normal heart function may be able to undertake a wide range of recreational activities.
Exercise recommendations may need to be modified if there is significant conduit obstruction, valve regurgitation, ventricular dysfunction, aortic enlargement or an important abnormal heart rhythm.
If you are considering competitive sport, very high-intensity exercise or heavy resistance training, discuss this with your congenital cardiologist.
Look after your teeth
Excellent dental hygiene and regular dental care are particularly important.
Some people with repaired truncus arteriosus have prosthetic valves or valve-containing conduits and are at increased risk of infective endocarditis.
Depending on your repair, you may require antibiotics before certain dental procedures.
Your congenital cardiologist or dentist can tell you whether antibiotic prophylaxis applies to you.
Don’t smoke or vape
Avoid smoking and vaping. Maintaining a healthy weight, blood pressure and cholesterol is also important for long-term cardiovascular health.
Pregnancy
Many women with successfully repaired truncus arteriosus can have a successful pregnancy, but the risk varies considerably depending on their current heart condition.
Pregnancy places additional workload on both ventricles and the heart valves.
Risk may be higher when there is:
Significant RV–PA conduit obstruction or pulmonary regurgitation
Reduced right or left ventricular function
Significant truncal/aortic valve regurgitation
Significant aortic enlargement
Pulmonary hypertension
Important abnormal heart rhythms
Women with repaired truncus arteriosus should have specialist pre-pregnancy assessment with an adult congenital heart disease and pregnancy team.
This also provides an opportunity to determine whether any valve or conduit intervention would be better performed before pregnancy.
Does truncus arteriosus run in families?
Most cases of truncus arteriosus occur without another affected family member.
However, truncus arteriosus has an important association with some genetic conditions, particularly 22q11.2 deletion syndrome.
If you have truncus arteriosus and are considering having children, genetic counselling may be appropriate.
People born with congenital heart disease also have a higher chance of having a child with congenital heart disease than the general population.
A specialised ultrasound of the baby’s heart (fetal echocardiogram) is usually recommended during pregnancy.
Symptoms to tell your doctor about
Contact your doctor or congenital cardiology team if you develop:
New or increasing shortness of breath
A noticeable reduction in exercise capacity
Frequent or prolonged palpitations
Dizziness or near-fainting
Unexplained fainting
New swelling of your ankles or abdomen
Increasing fatigue
Persistent unexplained fever
A significant change in your usual symptoms
A gradual reduction in exercise capacity may be an early sign that a conduit or valve is becoming more significantly narrowed or leaky.
Persistent unexplained fever is important because people with prosthetic valves or conduits can be at risk of infective endocarditis.
Emergency — get help immediately if
Seek urgent medical attention or call 000 if you develop:
Severe or rapidly worsening shortness of breath
Fainting during exercise
Fainting associated with palpitations
A sustained rapid heartbeat associated with dizziness or feeling very unwell
Severe chest pain
High fever with shaking chills and feeling seriously unwell
A sudden significant deterioration in your condition
Your regular check-ups
Follow-up for repaired truncus arteriosus may include:
Clinical review
Your cardiologist will ask about exercise capacity, breathlessness, palpitations and other symptoms and examine your heart and circulation.
ECG
An electrocardiogram records the electrical activity and rhythm of your heart.
Echocardiogram
An ultrasound can assess ventricular function, the RV–PA conduit, pulmonary valve and truncal/aortic valve and estimate pressures within the heart.
Cardiac MRI
Cardiac MRI is particularly useful for measuring right and left ventricular size and function, pulmonary regurgitation, blood flow and the anatomy of the pulmonary arteries and aorta.
Cardiac CT
CT may provide additional information about the conduit, pulmonary arteries, aorta and coronary arteries, particularly when planning an intervention.
Exercise testing
Cardiopulmonary exercise testing can objectively assess exercise capacity and help identify changes over time.
Heart rhythm monitoring
A Holter monitor or longer-term rhythm monitor may be recommended if you experience palpitations, dizziness or fainting.
Cardiac catheterisation
Catheterisation may be used to measure pressures, assess anatomy or perform treatments such as pulmonary artery stenting or transcatheter pulmonary valve replacement.
Questions for your doctor
How well is my RV–PA conduit functioning?
Do I have pulmonary stenosis or pulmonary regurgitation?
Are my right and left ventricles normal in size and function?
Is my truncal/aortic valve leaking or narrowed?
Is my aortic root enlarged?
Am I likely to need another conduit or pulmonary valve procedure?
Could a future pulmonary valve be replaced using a catheter rather than surgery?
Do I need antibiotics before dental treatment?
Do I have any restrictions on exercise, work, travel or pregnancy?
How often should I have congenital heart follow-up?
This information is intended as a general guide for teenagers and adults with repaired truncus arteriosus. Individual anatomy and previous operations vary considerably, and your congenital cardiologist can provide advice specific to your repair, conduit, heart valves and current health.
